Immune response to vaccinia virus and recombinant virus products in dogs

A study was undertaken to determine the safety and suitability of vaccinia virus as an eukaryotic expression vector in dogs. Clinical signs were not seen in inoculated dogs, with the exception of small nodules at the site of inoculation. Vaccinia virus did not spread from dogs that were inoculated by SC (n = 5), intradermal (ID; n = 13), or intranasal (n = 3) routes to noninoculated dogs maintained in close contact. Replication of vaccinia virus appeared to be restricted in dogs because greater than or equal to 10(5) plaque-forming units of virus were required to induce an immune response by ID inoculation. Results were better with ID inoculation than with SC or intranasal inoculations. Repeated inoculations enhanced serum antibody titers, and annual reinoculation resulted in boosting of antibody titers. Maternal antibody interfered with virus replication and antibody production. Recombinant virus products induced antibody formation in dogs to human influenza-A virus, herpes simplex virus, and human hepatitis-B virus antigens. It was concluded that vaccinia virus would be safe and suitable as an eukaryotic expression vector in dogs.